Circuit interrupter



, April 28, 1936. .1. w. HUFFSTUTTER CIRCUIT INTERRUPTER Filed March1'7, 1954 l l. .n /9 .l Il /9 l. n. 39 529 6, 3j//.V////'///////y/////////////////,f

ITNESSES;

Patented Apr. 28, 1936 PATENT OFFICE CIRCUIT INTERRUPTER JohnW.'Huistutter, Pitcairn, Pa., assigner to Westinghouse Electric &Manufacturing Company, East `Pittsburgh, Pa., a. corporation ofPennsylvania Application March 17, 1934, serial No. 716,071

13 Claims.

My invention relates generally to circuit interrupters and particularlyto circuit breakers wherein the arc which is established incident tothebpening of the controlled circuit is extinguished within a narrowslot type arc extinguisher.

This type of arc extinguisher is a comparatively recent development inthe art of circuit interruption, although the principles on which itoperates have been known for a number of years.

Essentially, the device comprises a substantially closed chamber ofnarrow width which is formed by the proper positioning of a pair ofopposed wall members having a relativelylarge area. The wall members areusually substantially fiat and are positioned in parallel planes, whichare disposed in proximity to each other'. The space enclosed by thesewall members thus comprises a very narrow passageway having a largesurface area and a small volume. The breaker contact members aremovablewithin this passageway to establish an arc therein.

In the preferred form, the inner surfaces of walls of the passage areformed of a gas evolving material, and immediately upon the establishingof the arc, this material decomposes to form a blast of arcextinguishing gas which flows lateraly through the arc with an expulsiveaction and thereby effects its extinguish- The operation of thesedevices has proven very satisfactory under most ordinary circuitconditions, but one diiiiculty has arisen, due to the particularcharacteristics of the device. -The 35 blast of arc extinguishing gaswhich effects the extinguishment of the arc results directly from theheating produced by the arc itself, and as a result, the volume of thisgas is almost a direct function of the intimacy of contact between the40 gas evolving walls and the outer surfaces of the arc. Furthermore,the physical dimensions of an electric arc depend, under ordinaryconditions, upon the magnitude of current flowing through the arccircuit. Thus, if a narrow slot 45 type circuit interrupter is toeffectively extinguish an arc, it is necessary that the spacing of thewalls be not greater than the mean diameter of the smallest arc whichmay be drawn therein, because if the walls are spaced apart further 50than this, an adequate gas blast will not be pro-l While it isimperative that the walls be spaced sufficiently close together toassure an adequate gas blast when interrupting low current arcs, it isequally important that the spacing of the walls be sufficiently great toprevent the production of dangerous internal pressures which i mightdamage the device when interrupting arcs of large current magnitude. Theresult of these conflicting requirements has been the production of acircuit interrupter which was operable 10 over a rather limited range ofcurrent values, especially in the higher voltage ratings, and theprincipal object of my invention is to provide a narrow slot circuitinterrupter which shall be capable of extinguishing arcs whose current15 magnitude may vary over a considerable range.

' In accomplishing this object of my invention, I provide a circuitinterrupter having the conventicnal narrow slot chamber wherein the arcis established, and a means for establishing an '20 arc within thatchamber. In contrast to the usual form of narrow slot arc extinguisher,however, wherein the passage is of substantially uniform width, Iprovide a device wherein the arc passage has at least one portion ofless width 25 than the remaining portions thereof, and I provide meanswhereby, during the operation of the interrupter, the arc is initiallyestablished externally of the portion of least width and is then drawninto that portion, if not already extinguished. This arrangement permitsthe operation of a narrow slot type arc extinguisher over a very widerange of current values. Arcs of large current magnitude areextinguished within the wider portions of the arc chamber without theproduction of excessive volumes of gas or dangerous internal pressureswhich might tend to mechanically injure `the device and if the magnitudeof the arc is low, its ultimate extinguishment is still assured byvirtue of the fact that it is drawn into the narrow portion of thechamber subsequent to its. being established within the wider portion.

It is, of course, within the province of my invention that a. narrowslot arc extinguisher having a plurality of portions each progressivelysmaller in width than the preceding portion could be provided. Throughthe'arrangement, the range of arc current magnitudes which 5 might besuccessfully interrupted by the device could, of course, be extended toany desired value.

' A further object of my invention is to provide an improved contactstructure particularly suitable for use with the narrow slot arcextinguishing device oi' my invention.

An ancillary object of my invention is to provide an improved lining fora narrow slot arc. extinguishing device constructed according to theprinciples of my invention, my improved lining to increase the arcextinguishing efiiciency of the device and to minimize any danger fromfire or the` like.

These and other objects of my invention will be made more apparent byreference to the accompanying drawing, wherein Figure 1 is anelevational View of a single pole circuit interrupter embodying theprincipal features of mv invention, a portion of one oi the side wallshas been cut away to more clearly illustrate the structural featuresinvolved.

Fig. 2 is an elevational view of one of the two wall members whichtogether make up the narrow slot arc extinguisher shown in Fig. 1, andthe contact structure of the device shown in that figure. The contactsare in the fully closed position.

Fig. 3 is an elevational view similar to Fig. 2 except that the contactsare in the partially open position.

Fig. 4 is a view likewise similar to Fig. 2 eX- cept that the contactsare in the fully open position.

Fig. 5 is a sectional view on the line V-V of Fig. 2, and

Fig. 6 is a sectional view on the line VI-VI of Fig. 3`

The preferred embodiment of my invention illustrated in the drawingcomprises, generally, a pair of wall defining members I, of insulatingmaterial which are adapted to be spaced apart by three rectangularmembers 3, 5, and 1 of insulating material to form a narrow passageway 9having considerable surface area. This passageway 9 is open at the top,which is the direction toward `which the arc is moved during the normaloperation of the device, and is substantially closed on the other threesides by the spacing members 3, 5 and 1. A plurality of bolts whichextend through suitable openings in the wall defining members I and thespacing members 3, 5 and 1, are provided for holding the wall deningmembers and the spacing members in position, and three bolts |3 whichextend through insulating sleeves l5 positioned in the wall members Iare provided for preventing the internal pressures developed within thedevice from causing a bulging of the walls. Suitable metallic washers l1serve to increase the effective contact area of the bolts I3.

'I'he inner surface ot each of the two wall members I is lined with aplurality of tile-like members I9 of compressed borlc acid which arecemented or otherwise securely aiiixed to the opposed inner surfaces ofthose members. As is shown particularly in Figs. 5 and 6, the tile-likemembers I9 in the left hand portion 2D of the narrow passageway 9 arethinner than the similar tile-like members I9 'in the right hand portion2l of the passageway. Thus, the passagel wherein the arc is drawn isdivided into two portions, one of which (2|) is considerably less widththan the other. This arrangement makes possible the eiiicient operationof the device when interrupting arcs of either of large or small currentmagnitude.

The contact structure comprises a pair of separable contacts 23 and 25,each of which is provided with a curved arsing horn 21 and a maincurrent carrying portion. The left hand contact 23 is rigidly affixed tothe wall members I oi the arc extinguishing device by a bolt 26 and aninsulating sleeve 28 and is normally adapted to remain stationary duringthe operation of the interrupter. The right hand contact 25 includes, asmentioned above, a similar arc horn 21 and a movable main contact member29 which is adapted to be engaged at the right hand end by the breakeroperating mechanism (not shown). The right hand arcing horn 21 issupported upon this main contact member 29 and is movable with respectthereto. A substantially U-shaped saddle 3| extends down from the righthand arcing horn 21 and serves to aid in guiding the movement of thatmember lwith respect to the main contact member 29, and a pair ofsprings 32 bias the arcing horn so that the sides of the downwardlyprojecting saddle 3| tend to engage a pair of stop members 33, one ofwhich is disposed on either side of the main Contact member 29. Thestationary Contact 23 is provided with a pair of opposed resilient jaws35 for engaging the current carrying surfaces 36 of the main contactmember 29 when the breaker is in the closed circuit position, and aflexible shunt 31 serves to electrically connect the right hand arc horn21 with the main moving contact. All portions of the moving contact 25which move through the narrow portion 2| of the passageway 9 are ofslightly less Width than that portion of the passageway in order that nofriction or interference shall develop during the operation of theinterrupter.

The circuit breaker contacts are shown in the closed circuit position inFig. 2. During the circuit opening operation, the main moving contactmember 29 is moved by the operating mechanism from the position shown inFig. 2 toward the position shown in Fig. 4. The initial portion of thismovement causes the current carrying surfaces 36 of the main movingcontact to disengage the cooperating jaws 35 afiixed to the stationarycontact 23. This portion of the movement does not, however, open thecircuit through the interrupter, by virtue of the fact that the righthand arcing horn 21 is movable with respect to the main movable contactmember 29, and by virtue oi the fact that the springs 32 bias the righthand are horn. 21 into engagement with the cooperating left hand arcinghorn. Further movement of the main current carrying member 29 of themovable contact 36 causes the stops 33 to engage the sides of the saddle3|,

whereupon the right hand arcing horn disengages the left hand arc hornand moves to the position shown in Fig. 4. The circuit interrupter isthen in the fully open position.

An arc is established immediately upon the separation of the arc horns21 and by virtue of the location of those members, is initiallyestablished within the wider portion 2U of the narrow passage 9. Theheat of the arc decomposes the boric acid lining of the opposed sidewalls, end if the magnitude and physical dimensions of the arc aresu'licient to intimately contact those walls, produces a very largeoutiiowing blast of arc extinguishing gas. Since the arc extinguishingdevice is substantially closed on all sides except the top and since thecontour of the arcing horns 21 is such that the magnetic effect of thearc current tends to move the are upwardly along those horns, theoutfiowlng gas produced by the decomposition of the walls flowslaterally through the arc as it escapes, and the arc is extinguishedwithin a very short interval of time.

If the magnitude of the arc current is insumcient to effect anextinguishment of the arc in the wider portion 20 of the narrow passage9, the movement of the right hand arcing horn 21 during the final stagesof the circuit opening operation causes the arc to be drawn into thenarrower portion 2l of the passage, wherein it intimately contacts theadjacent walls and its extinguishment is effected.

The operating mechanism for use with this type of circuit interrupter isnot an important part of my invention, and any means whereby the mainmovable contact 29 can be moved from one position'to the other may beused. It is preferable that the contact be moved to the open position athigh speed, although at least one or two cycles should elapse before thearc is drawn into the narrower portion 2| of the passageway in orderthat suincient time r'nay be allowed for extinguishing the large currentmagnitude arcs in the wider portion 2U of the passageway.

Both the right hand arc horn 21 and the main moving contact 29 areadapted to move within an opening 39 formed in the side member 1. The

sides of this opening 39 slidably engage the sides of those members andserve, in conjunction with the operating mechanism, to accurately guidethe movable contact 25 during the operation of the interrupter,

It should be noted that while the several current carrying portions ofthe contacts 23land 25 are formed from relatively thin sheets ofconducting material, the cross sectional area of the current carryingportions of those contacts is quite large. This is of courseaccomplished by providing members which are wide in a plane parallel tothe planes of the wall defining members 29.

The lining of the passageway 9 is preferably of boric acid, as statedabove, because that material, when placed in proximity to an electricarc, evolves a, large quantity of an arc extinguishing gas which issubstantiallyinorganic in composition. It is, of course, within theprovince of my invention that other solid materials might be used forsecuring this gas blast. Another advantage of boric acid arises from thefact that substantially all of the gas evolved is non-inflammable, andfrom the fact that the surface of boric acid when exposed to the actionof an electric are does not become conducting. Thus, any possibility ofthe device short circuiting itself during operation is prevented.

From the foregoing, it will be seen that I have disclosed a new andimproved circuit interrupter which utilizes the narrow slot principle ofarc extinction much more efiiciently than the devices previously knownto the art. My improved circuit interruptor is capable of eicientoperation over a very wide range of arc current values and', at the sametime, is relatively simple in design and inexpensive to manufacture. Inaddition, I have disclosed an improved contact structure which isparticularly suitable for use with all types of narrow slot type circuitinter# rupters wherein relatively heavy currents have to be carriedduring the normal operation of the device. K

While, in accordance with the patent statutes, I have disclosed theforegoing details of a preferred embodiment of my invention, it is, tobe understood that many of these details are merely illustrative andthat variations in their precise form will be both necessary anddesirable for certain applications. It is my desire, therefore, that thelanguage of the accompanying claims shall be accorded the broadestreasonable construction, and that my invention shall be limited only bywhat is vexpressly stated therein and by the prior art.

I claim as my invention:

1. In a circuit interrupter, a pair of wall members of extended surfacearea, means for supporting said wall members in close proximity to eachother so as to define the opposed walls of a narrow passageway, theWidth of at least one portion of said passageway being less than thewidth of the remaining portions thereof, and means comprising contactmeans movable in said portion of less width and in said remainingportions to establish an arc within said passageway, said arc beinginitially established externally of the narrow portion of saidpassageway and a portion thereof being subsequently drawn within thesaid narrower portion of said passageway, said arc drawing meanscomprising conducting means at least a portion of which has a width notgreater than the width of the narrower portion of said passageway.

2. In a circuit interrupter, means defining a pair of wall members ofconsiderable surface area, means for supporting said wall members inclose proximity to each other so as to define the opposed walls of anarrow passageway, said wall members being so formed and so positionedthat at least one portion of said passageway is of less width than theremaining portions thereof, contact means movable within said portion ofless width and within said remaining portions to establish the arcincident to each opening of said interrupter within said passageway,said arc being initially established externally of said portion of lesswidth and being subsequently drawn within said portion of less width ifnot already extinguished, at least one of said wail defining membersbeing lined with a solid material that is capable of evolvingconsiderable quantities of an arc extinguishing gas when placed inproximity to an electric arc, and means for so venting said passagewaythat substantially all the gas which is evolved from said lining iscaused to flow laterally through said arc during the progress of thecircuit opening operation.

3. In a circuit interrupter, means defining a pair of wall members ofconsiderable surface area, means for supporting said wall members inclose proximity to each other so as to define the opposed walls of anarrow passageway, the opposed surfaces of said wall defining membersbeing disposed substantially parallel to each other and being so formedthat at least one portion of said passageway is of less width than theremaining portions thereof, contact means movable within said portion ofless width and within said remaining portions to establish the arcincident to each opening operation of said interrupter within saidpassageway, said arc being initially established externally of saidportion of less width and being subsequently drawn within said portionof less width if not already extinguished, at least one of said walldefining members being lined, at least in part, with a solid materialthat is capable of evolving an arc extinguishing gas when placed inproximity to an electric arc, said gas evolving lining extending acrossa substantial portion oi' said portion of less Width and said remainingportions of said passageway, and means for so venting said passagewaythat substantially all of the gas which is evolved from said lining iscaused to flow laterally through said arc 'during the progress of thecircuit opening operation.

4. In a circuit interruptor, means defining a pair of wall members ofconsiderable surface area, means for supporting said wall members inclose proximity to each other so as to denne the opposed Walls of anarrow passageway, said wall members being so formed and so positionedthat at least one portion of said passageway is of less width than theremaining portions thereof, contact means movable within said portion ofless width and said remaining portions to draw an arc within saidpassageway, means for moving said arc laterally within said passageway,and means for substantially totally enclosing said passage except forvents disposed adjacent the side toward which the arc is moved by saidarc moving means.

5. In a circuit interrupter, means including a pair of oppositelydisposed wall members of considerable surface area for dening the wallsof a narrow passageway, said wall defining members being so formed andso positioned that at least one portion of said passageway is o! lesswidth than the remaining portions thereof, a substantial portion of theinner surface of at least one of said wall defining members, both insaid portion of less width and in said remaining portions, being linedwith a material which is capable of evolving an arc extinguishing gaswhen placed in proximity to an electric arc, contact means movable inboth portions of said passageway to establish an arc having a portionWithin said portion of less width and a portion within said remainingportions, said portion of said arc which is established within saidportion of less width being drawn subsequently to said other portion ofsaid arc, and means for so venting said passageway that the gas evolvedfrom said lining is caused to flow simultaneously through said portionof less width and said rcmaining portions in order to move said arclaterally theren during the progress of cach cir cuit opening operation.

6. In a circuit interrupter, means including a pair of opposed wallmembers of considerable area for defining the walls of an are passagewhich has the substantial form of two connecting rectangularparallelopipecls of diilcring thicknesses, the surface area of saidopposed wall members being at least several times the cross sectionalarea of said arc passage along either the longitudinal or the verticalaxis thereof, a substantial portion of the inner surface of at least oneof said wall members being lined with a material which is capable ofevolving an arc extinguishing gas when placed in proximity to anelectric arc, contact means movable both portions cf said passageway toestablish an arc having a portion within said wider portion and aportion within said narrower portion of said arc passage, and means forventing said passage in such manner that the gas evolved from saidlining effects a substantial lateral movement of the portion of said arcwhich is drawn within each of said portions of said passage during theprogress of each circuit opening operation.

7. In a circuit interrupter, means including a pair of oppositelydisposed plate members of considerable surface area for defining thewalls of a narrow passageway, said wall defining members being so formedand so positioned that at least one portion of said passageway is ofless width than the remaining portions, means for substantiallycompletely enclosing said passageway except for venting means locatedadjacent one end thereof, a substantial portion of the inner surface ofat least one of said plate members in said portion of less width and insaid remaining portions being lined with a material which is capable ofevolving an arc extinguishing gas when placed in proximity to anelectric arc, and contact means movable in both portions of 4saidpassageway to establish an are having a portion within said portion ofless Width and a portion within said remaining portions, said portion ofsaid arc which is established within said portion of less Width beingdrawn subsequently to said other portion of said arc, said venting meansbeing so arranged that the gas evolved from said lining by the heat ofsaid arc is caused to flow laterally through said portion of less widthand said remaining portions during each circuit opening operation, theportion of said arc' which is established within said portion of less'width and within said remaining portions being thereby moved laterallya considerable distance within said passageway during the progress ofeach cir cuit opening operation.

8. In a circuit interrupter, means including a pair of oppositelydisposed plate members of considerable surface area for defining thewalls of a narrow passageway, said wall defining members being so formedand so positioned that said passageway comprises a pair of connectingrec ltangular parallelopipeds, means for substantially enclosing saidarc passage except for venting means located adjacent one end of each ofsaid rectangular paralielopipeds, a substantial portion of the innersurface of at least one of said plate members being lined with a solidmaterial which is capable of evolving an arc extinguishing gas whenplaced in proximity to an electric arc, means including a pair ofseparable contacts for establishing an arc within said passage adjacentone of its closed sides, said arc drawing contacts being movable withinboth of said parallelopipeds in order that said arc shall be initiallyestablished within said parallelo piped of greater width and that aportion of said arc shall be subsequently established within saidparallelopiped of less width, said venting means being so arranged thatthe gas evolved from said lining by the heat of said arc is caused to owlaterally through each of said connecting parallelopipeds during eachcircuit opening operation, the portion cf said arc which is drawn within'each of said peraliciopipeds being thereby moved laterally in thedirection of said vented end during the progress of the circuit openingoperation.

9. In a circuit interrupter, means, including a pair of oppositelydisposed wall members of considerable surface area, for denng the wallsof an arc chute, said wall defining members being sovformed and sopositioned that at least one portion of the passageway within said chuteis of less width than the remaining portions thereof, a substantialportion of the inner surface of said wall defining means both in saidportion of less width and in said remaining portions being lined with asolid material which is capable of evolving an arc extinguishing gaswhen placed in proximity to an electric arc, means for establishing theare incident to each opening operation of said interrupter within saidare chute,-one portion of said arc being established within said portionof less width and another portion of said arc being established withinsaid remaining portions, and

ing lined with a solid material which is capablel of evolving an arcextinguishing gas when placed in proximity to an electric arc, means forestablishing the arc incident to each opening operation of saidinterrupter within said arc chute, one portion of said arc beingestablished within said portion of less width and a second portion ofsaid arc being established within said por-- tions of greater width,diverging arc horns disposed within said arc chute for providing termi-A nals for the ends of said arc, and means for causing said arc to bemoved laterally on said arc horns to effect its extinguishment duringeach operation of said interrupter,

11. In a circuit interrupter, means, including a pair of oppositelydisposed wall members of considerable surface area, for defining thewalls of an arc chute, said wall defining members being so formed and sopositioned that at least a portion of the passagewaywithin said arcchute is of less width than the remaining portions thereof, asubstantial portion of the inner surface of said wall defining meansboth in said portion of less width and in said remaining portions beinglined with a solid material which is capable of evolving an arcextinguishing gas when placed in proximity to an electric arc, means forestablishing the arc incident to each opening operation of saidinterrupter within said chute, said arc establishing means drawing aportion of said arc within said portions or portions of greater widthand subsequently drawing a portion of said arc into said portion of lessWidth, diverging arc horns disposed within said arc chute for providingterminals for said arc, and means for venting said chute in such mannerthe gas evolved from said lining effects a substantial lateral movementof said arc on said arc horns during the progress of each circuitopening operation, said portions of less width and said portions ofgreater width being arranged side by side and extending in the directionin which said arc is moved on said arc horns in order that the portionof said arc which is established within each oi' the portions of saidpassageway shall remain therein throughout the entire arc extinguishingoperation.

12. In a circuit interrupter, means, including a pair of oppositelydisposed wall members of considerable surface area, for defining thewalls of an arc chute, the passageway within said chute having asubstantial form of two, connecting, rectangular parallelopipeds, thesurface area of said opposed Wall members being at least several timesthe greatest cross sectional area of said arc passage alongeither thelongitudinal or the vertical axis thereof, a substantial portion of theinner surface of said wall defining means being lined with a materialwhich is capable of evolving an arc extinguishing gas when placed inproximity to an electric arc, means for establishing the arc incident toeach opening operation of said interrupter within said arc chute, saidarc being initially established within said parallelopiped of greaterthickness and a portion thereof being subsequently established withinsaid parallelopiped of less thickness, diverging arc horns disposedwithin said chute for providing terminals for said arc, and means forventing said chute in such manner that the gas evolved from said liningeffects a substantial lateral movement of the portion of said arc whichis drawn within each of the portions of said passageway during theprogress of each circuit opening operation.

13. In a circuit interrupter, means, including a pair of oppositelydisposed wall members of considerable surface area, for defining thewalls of an arc chute, said wall defining means being so formed that atleast one portion of said passageway is of less width than the remainingportions thereof, a substantial portion of said wall defining means bothin said portion of less width and in said remaining portions being linedwith a material which is capable of evolving an arc extinguishing gaswhen placed in proximity to an electric arc, means for establishing thearc incident to each opening operation of said inter-- rupter withinsaid arc chute, one portion of said arc being established within saidportion of greater width and another portion of said arc beingestablished within said portion of less Width, diverging arc horns, oneof which is disposed within said portion of greater width and one ofwhich is disposed within said portion of less width during at least thefinal stages of each circuit opening operation, for providing terminalsfor said arc, and means for venting said chute in such manner that thegas evolved from said lining effects a substantial lateral movement ofsaid arc on said arc horns during the progress of each circuit openingoperation.

JOHN W. HUFFSTUTTER.

